The overall aim of this project is to develop a new bioreactor for perfusion cell culturing. A bioreactor is a system for growing large volumes of cells in-vitro and harvesting their by-products such as monoclonal antibodies, enzymes, hormones, vaccines and other proteins for commercial and research applications. The bioreactor to be developed under this SBIR grant will be a composite of two Replamineform materials, porous hydroxyapatite and porous silicone rubber. Cells will be grown on the hydroxyapatite and perfused with nutrients through an interpenetrating network of porous silicone rubber channels. Hydroxyapatite offers biocompatibility, cytophilia, heat and mechanical stability and adsorption high molecular weight proteins. Silicone rubber as the semipermeable membrane offers biocompatibility, heat and mechanical stability, wettability and high respiratory gas transfer. The specific aim of this Phase I SBIR grant is to develop prototype bioreactors. These prototypes will be evaluated by scanning electron microscopy, perfusion testing, and cell culturing against fibroblasts and bacterial cultures. This SBIR grant should improve the manufacturing efficiencies of cell culturing by increasing cell densities and by decreasing media consumption, potential for microbial contamination, capital costs and purification losses.